Environment and Breast Cancer: Science Review

Evidence From Humans
Print this page
Organochlorine exposure and age at natural menopause
Cooper, G. S., Savitz, D. A., Millikan, R., Chiu Kit, T. Epidemiology. 2002. 13:6, 729-33.
Topic area
Environmental pollutant - Environmental pollutant, DDT, DDE
Study design
Population based case-control
Funding agency
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number of Controls
Controls: 659
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Participants of the Carolina Breast Cancer Study. Breast cancer cases were identified through the North Carolina Central Cancer Registry. Controls were randomly selected using Division of Motor Vehicles and Medicare beneficiary lists.
Exposures investigated
Lipid-corrected plasma levels of organochlorines (DDE and PCBs)
Statistical Analysis
Breast cancer outcome investigated
Other: Age at natural menopause.
Ethnic groups with separate analysis
If this study provided a separate analysis by ethnic or racial group, the groups are listed here.
Confounders considered
Other breast cancer risk factors, such as family history, age at first birth, and hormone replacement therapy use, that were taken into account in the study.
Age at interview, race, education, parity and lactation, physical activity, thyroid condition, BMI, and smoking.
Genetic characterization included
If the study analyzed relationships between environmental factors and inherited genetic variations, this field will be marked “Yes.” “No”, if not.
Description of major analysis
Analysis was limited to post-menopausal women. Time to natural menopause was examined using proportional hazards modeling as a function of age. Cases and controls were analyzed separately, but results were combined once the patterns of association prove
Strength of associations reported
For DDE the hazard ratios increased monotonically, results were consistent between categorical and continuous analyses, and the effect estimate in the highest category of DDE exposure was HR = 1.4, 95% CI: 0.9-2.1. This effect was similar to that seen for smoking (HR = 1.4, 95% CI: 1.1-1.9).

There was little evidence of an association between PCB exposure and age at natural menopause.
Results Comments
The effect of DDE on age at natural menopause corresponds to an approximately 1-year difference in the median age at natural menopause, comparing the highest category of DDE exposure to the lowest.
Author address
Epidemiology Branch, National Institute of Environmental Health Sciences, Durham, NC, USA. cooper1@niehs.nih.gov